1. Technical Field
This invention relates generally to incandescent light bulbs used for automotive applications.
2. Related Art
U.S. Pat. No. 6,469,443 discloses an incandescent light bulb for use in automotive turn signal applications in which light-emitting elements are sealed within a glass envelope and are coupled electrically by lead-in wires which pass through the envelope to the exterior thereof for connection with a source of electrical energy. The glass envelope is a barium silicate based glass that is essentially free of cadmium and includes a certain amount of strontium to give the glass an amber color. While such envelope material has shown to be useful for its intended purpose, it has been found that the glass material is generally incompatible with many of the existing lead-in wire materials such that over the course of repeated heating and cooling cycles of the lamp assembly, the lead-in wires are caused to separate and then reengage the envelope material so as to introduce a build-up of stress, cracking and/or failure of the envelope glass at the interface of the lead-in wires and envelope. It is an object of the present invention to overcome or greatly minimize the disadvantages associated with employing barium silica glass envelopes for such lighting applications.